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Agronomy Journal Abstract -

Variation in Taproot Elongation Rate as Influenced by Composition of the Soil Air1


This article in AJ

  1. Vol. 62 No. 6, p. 815-818
    Received: May 11, 1970

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  1. M. G. Huck2



Elongation rates of cotton and soybean taproots were measured while the O2 content of a gas stream passing through the soil surrounding the roots was varied. Elongation rates were comparable to controls at all O2 concentrations above 10%. Elongation ceased completely within 2 to 3 min after all O2 was purged from the system with 100% N2 gas, and returned to normal shortly after 21% O2 was returned to the system, provided the period of anaerobiosis had not exceeded 30 min. Longer periods of complete anaerobiosis resulted in killing of a certain percentage of root tips until approximately 100% of the primary taproots were killed at 3 hr without O2 for cotton and 5 hr for soybeans. Oxygen levels from 2 to 5% resulted in an initial reduction in rate of taproot extension, followed by a gradual return to elongation rates comparable with controls. Although 3 to 5 hr of complete anaerobiosis evidently killed the terminal meristematic region of the taproots, new lateral growth developed from the cortex within a day or two after cessation of growth of the terminal meristems. Distribution of roots through a volume of soil may thus be influenced by oxygen availability and its distribution through time and space.

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